When I first heard Peter Hain speak, in the autumn of 1993, he was a passionate figure in a beaten-up leather jacket. Perched on a table at Sussex university, where he read for a master's degree, he spoke urgently of the need to drive John Major's government out.

He was not in good odour with the party leadership at the time: Gordon Brown had just engineered his removal as secretary of the Tribune group after Hain criticised his pro-European stance. The Neath MP left us in no doubt that he was an outsider with a radical edge.

He had to. Everyone in the Labour party remembers that Hain had once been president of the Young Liberals. He joined Labour late, at the age of 27, and under the influence of Neil Kinnock. Hain probably thought his struggles against the apartheid regime in South Africa - which, at one point, almost put him in jail - would enable him to convince most of the party of his radicalism. He was wrong. Agitation wins few hearts in the New Labour party. As many saw it, Hain was a would-be career politician who switched sides when it suited him.

Comparisons with Peter Mandelson, another suave individual who never won over the party, are misleading. Mandelson's grandfather was a Labour cabinet minister and was among the first people to grasp what made Labour unelectable and what compromises it would take to achieve power. Hain had a good grasp of Labour's weaknesses, too, though he defended the party's links with the trade unions longer than was wise. But he was hamstrung by the constant need to portray himself as an authentic Labour believer. When the party finally broke through in 1997, it wasn't the radicals who were in charge.

The 'permatan' caricature (which he blames on his youth in Kenya and South Africa) has proved impossible to shake off. And the charge of switching sides stuck. The vast majority of the current cabinet have moved a long way in political terms since their youth. So has Hain. But no one lets him forget it. He has been a careful and competent minister: he started out at the Welsh Office in 1997, moving through the Foreign Office and the DTI before taking on the work and pensions and Wales briefs under Brown. Many found Hain's support of the Iraq war and subsequent criticism of the way it was handled all too reminiscent of another politician with a habit of changing sides: Lord Owen. Indeed, for all the cultivated radicalism - and he throws that word around whenever he gets the chance - he is not a man given to outbursts.

When he stood for the deputy leadership last year, Hain probably thought that his impeccable ministerial record and long efforts to ingratiate himself with the Labour grassroots would pay off. He had not quite given up hope of winning over the party, which may explain why he spent so much on his deputy leadership campaign. He came fifth. It scarcely mattered: Brown decided he didn't want a deputy PM, and has kept Harriet Harman on a short leash. But it was a rejection that would prove prescient. When the undeclared donations emerged, Hain received very little support from his cabinet colleagues: Brown called him 'incompetent'. People have called Hain a lot of things - arrogant, clever, shameless - but no one had seriously accused him of incompetence before. The work and pensions secretary was doomed.